• KSBB Journal
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• v.17 no.3
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• pp.283-289
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• 2002

The present study was aimed at investigating the metabolic regulation of insulin-like growth factor-I(IGF-I) expression in fasting animals. The expression of IGF-I gene was determined by a solution hybridization/RNase protection assay using total RNA from control, 4d-fasting, and 2d-fasting-refed rats. The levels of IGF-I transcripts were reduced in 4d-fasting than in control by decreasing its transcriptional rate, which was measured through nuclear nun-on assay. DNase I footprinting, which was performed using nuclear extracts from fasting rat, demonstrated protein binding to a sequence that extended from +179 to +210 (termed region B). These data suggest that the expression of IGF-I is transcriptionally regulated through DNA-liver enriched protein binding in a sequence which is located downstream from major transcription initiation site of IGF-I gene.

• Korean Journal of Veterinary Research
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• v.46 no.2
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• pp.97-105
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• 2006

All-trans retinoic acid (AtRA) induces growth inhibition and apoptosis in a variety of tumer cells, including MCF-7 cells. Insulin-like growth factors (IGFs) system has been reported to be associated with the development of cancer. Although MCF-7 cell with AtRA is to be the major stimulus for the cell growth and apoptosis, the mechanism of insulin-like growth factor-I (IGF-I)/insulin-like growth factor binding protein-3 (IGFBP-3) system remains to be elucidated. Thus, this study was conducted to the effect of AtRA on the gene expression and level of IGF-I and IGFBP-3. In addition, we investigated the involvement of PKC-${\delta}$ on the IGF-I and IGFBP-3 secretion in MCF-7 cell. AtRA(${\geq}10^{-7}M$) decreased the IGF-1 secretion and mRNA expressions, but increased IGFBP-3 secretion and mRNA expressions in MCF-7 cells. Especially, the treatment of AtRA at 72 hours caused a significant reduction in the IGF-I secretion and mRNA expressions but increment in IGFBP-3 secretion and mRNA expressions (p < 0.05). $10^{-7}M$ AtRA activated PKC-${\delta}$ that is one among PKC-$\iota$, ${\alpha}$, ${\lambda}$ and ${\delta}$ in MCF-7 cell. Rotllerin, a PKC-${\delta}$ inhibitor, blocked AtRA-induced inhibition of the IGF-I and mRNA expressions, and increase of lGFBP-3 and mRNA expressions in MCF-7 cell. Together, AtRA inhibited the IGF-I secretion and mRNA expressions, but increased IGFBP-3 secretion and mRNA expressions in MCF-7 cell. Furthermore, AtRA-induced alteration of IGF-I, IGFBP-3 secretion, and the gene expressions were mediated via PKC-${\delta}$ activity.

• KSBB Journal
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• v.18 no.4
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• pp.329-334
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• 2003

The present study was aimed at investigating the regulatory mechanism in tissue-specific expression of insulin-like growth factor-I (IGF-I) gene. The expression of IGF-I gene was determined by a solution hybridization/RNase protection assay using total RNA prepared from rat liver or brain of various ages. The levels of IGF-I transcripts were increased in liver gradually after birth, but decreased in brain. By using an oligonucleotide (FRE) corresponding to the C/EBP binding site of the rat IGF-I exon 1, multiple forms of C/EBP${\alpha}$ and C/EBP${\beta}$ proteins, which have DNA-binding activity, were detected in the rat liver or brain. Western immunoblot and southwestern analyses show that p42$\^$C/EBP${\alpha}$/, p38$\^$C/EBP${\alpha}$/, p35$\^$C/EBP${\alpha}$/, p38$\^$C/EBP${\beta}$/, and p35$\^$C/EBP${\beta}$ form specific complexes with the IGF-I exon 1 oligonucleotide in liver nuclear extract and that p42$\^$C/EBP${\alpha}$/ and p38$\^$C/EBP${\beta}$/ form complexes in brain. These data suggest that the formation of FRE-C/EBP isoform complexes may play important roles in the tissue-specific regulation of IGF-I gene expression.

• Asian-Australasian Journal of Animal Sciences
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• v.23 no.3
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• pp.379-384
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• 2010

The principal objective of this experiment was to determine the effects of dietary betaine on IGF-I, IGFBP-3 and IGFBP-1 secretion and IGF-I mRNA gene expression in the serum and liver of laying hens. A total of 72 ISA-Brown laying hens were fed with four different levels of betaine (0, 300, 600, 1,200 ppm) based on a corn-soybean meal diet containing 2,800 kcal/kg of metabolizable energy (ME) and 16% crude protein (CP) for four weeks. The results indicated significantly higher serum and liver IGF-I concentrations in the laying hens fed with 600 and 1,200 ppm betaine (p<0.05) compared to controls. IGF-I gene expression in liver showed a statistically correlated increase in 600 and 1,200 ppm betaine-fed groups as compared to the controls (p<0.05). Serum IGFBP-3 concentrations were elevated significantly in the groups fed 600 ppm of betaine. However, the secretion of IGFBP-1 in the liver of laying hens fed on 600 and 1,200 ppm of betaine was significantly lower than in the controls (p<0.05). The results of this experiment showed that dietary betaine supplementation plays a pivotal role in changes of the IGFs system in laying hens.

• Molecules and Cells
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• v.28 no.5
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• pp.495-499
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• 2009

Although insulin-like growth factor-I (IGF-I) and androgen receptor (AR) are well known effectors of skeletal muscle, the molecular mechanism by which signaling pathways integrating AR and IGF-I in skeletal muscle cells has not been previously examined. In this study, the role of PI3K/Akt on IGF-I-induced gene expression and activation of AR in skeletal muscle cells was investigated. C2C12 cells were treated with IGF-I in the absence or presence of inhibitors of PI3K/Akt pathway (LY294002 and Wortmannin). Inhibition of the PI3K/Akt pathway with LY294002 or Wortmannin led to a significant decrease in IGF-I-induced AR phosphorylation and total AR protein expression. Furthermore, IGF-I-induced AR mRNA and skeletal ${\alpha}-actin$ mRNA were blocked by LY294002 or Wortmannin. Confocal images showed that IGF-I-induced AR translocation from cytosol to nucleus was inhibited significantly in response to treatment with LY294002 or Wortmannin. The present results suggest that modulating effect of IGF-I on AR gene expression and activation in C2C12 mouse skeletal muscle cells is mediated at least in part by the PI3K/Akt pathway.

• Asian-Australasian Journal of Animal Sciences
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• v.15 no.10
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• pp.1391-1394
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• 2002

The polymorphism of insulin-like growth factor-I (IGF-I) in 13 pig breeds (total n=559) was detected by PCR-Hha I- RFLP, and allele A (151 bp and 28 bp) or allele B (116 bp, 35 bp and 28 bp) were observed. In these pig breeds, it was found that European pig breeds carried high frequencies of allele B, while Chinese native pig breeds carried high frequencies of allele A. Meanwhile the role of porcine IGF-I was investigated in 117 Nanchang White pigs and 360 Large Yorkshire pigs. Eight traits about growth and carcass were recorded for analyzing the associations between IGF-I gene polymorphism and performance quantitative traits. In the Nanchang White pigs, those with AA genotype generally had higher birth weight than those with AB genotype (p<0.05), but all these genotypes had no significant effect on the other traits which had been analyzed. In Large Yorkshire pigs, those with BB genotype had higher 2 months and 6 months body weight than those with AA genotype (p<0.05), and had a thicker hind-back-fat thickness and mid-back-thickness than those with AB and BB genotypes (p<0.05). And those with BB genotype were the thinnest in Large Yorkshire. Furthermore, pigs with AA genotype had a lower lean percentage than those with AB and BB genotypes (p<0.01), and the lean percentage of those with BB genotype was the highest. Based on these results, it is possible to make the IGF-I gene locus into the application of marker-assisted selection programmes.

• Journal of Life Science
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• v.21 no.10
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• pp.1385-1392
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• 2011

It is well known that both insulin-like growth factor-I and suppressor of cytokine signaling-3 (SOCS-3) are known to modulate various aspects of physiology in skeletal muscle cells. Furthermore, although SOCS-3 expression is related to insulin resistance in non-skeletal muscle cells and is known to interact with insulin-like growth factor-I receptor, the effect of IGF-I on SOCS-3 gene expression in skeletal muscle cells is presently unknown. C2C12 myotubes were treated with different concentrations (0-200 ng/ml) of IGF-I or for various periods of time (3-72 hr). Immunofluorescent staining image revealed that IGF-I induced SOCS-3 protein expression in a dose-dependent manner. Western blot data also showed that SOCS-3 proteins were induced by IGF-I (200 ng/ml) in C2C12 myotubes in a time-dependent manner. The level of SOCS-3 mRNA was also significantly increased after 3hr of IGF-I (10-100 ng/ml) treatment. However, the levels of SOCS-3 mRNA were significantly decreased after 24 and 48 hr of IGF-I (10-100 ng/ml) treatment compared to the control. In conclusion, SOCS-3 protein is induced by IGF-I treatment in C2C12 skeletal muscle cells and this induction is regulated pretranslationally. The modulating effect of IGF-I on SOCS-3 expression may be an important regulator of gene expression in skeletal muscle cells.

• Asian-Australasian Journal of Animal Sciences
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• v.13 no.12
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• pp.1653-1658
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• 2000

Insulin-like growth factor-I (IGF-I) mRNA levels in the eyes, heart, liver and breast muscle removed from dwarf egg-type, normal egg-type and normal meat-type chicken embryos at 7, 14 and 20 days of incubation were measured. There was no influence of chicken strain on IGF-I gene expression in the eyes and liver. The IGF-I gene expression in eyes increased significantly along with the incubation period. In the liver, IGF-I gene expression at 20 days of incubation was significantly higher than that at 14 days of incubation. In the muscle, the lowest value for IGF-I gene expression was observed in meat-type chicken embryos. Regression analysis revealed that IGF-I gene expression was significantly correlated to the weights of the eyes and liver, but not the muscle. We conclude that there is little influence of strain on tissue IGF-I gene expression in chicken embryos during incubation but that tissue development in chicken embryos is nevertheless at least partly regulated by the change in IGF-I gene expression.

• Asian-Australasian Journal of Animal Sciences
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• v.11 no.3
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• pp.245-248
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• 1998

The influence of refeeding either protein, carbohydrate or fat on hepatic insulin-like growth factor-I (IGF-I) mRNA level in chicks which had been fasted for 2 days was examined. The hepatic IGF-I mRNA was measured by ribonuclease protection assay. Fasting reduced hepatic IGF-I mRNA levels to less than half of those in the fed control. When chicks were refed either a control, protein or carbohydrate diet, IGF-I mRNA levels significantly increased to those in the fed control until 2 hours of refeeding. Refeeding of fat did not alter hepatic IGF-I mRNA levels. The significant correlation between liver weight and hepatic IGF-I gene expression suggests that when chicks are refed after 2-d fasting, the acute increase in hepatic IGF-I gene expression brought about after refeeding may be partly regulated by the increase in liver protein metabolism.

• Asian-Australasian Journal of Animal Sciences
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• v.17 no.3
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• pp.301-304
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• 2004

The polymorphism of insulin-like growth factor I (IGF I) in 6 chicken breeds (total n=515) was detected by PCR-Pst IRFLP, and allele A (621 bp) or allele B (364 and 257 bp) were observed. In these chicken breeds, it was found that exotic chicken carried high frequencies of allele B, while Chinese native chicken breeds carried high frequencies of allele A. Meanwhile the role of IGF I was investigated in 133 Ningdu Yellow chicken and 162 Wanzhai Yellow chicken. Five growth traits were recorded for analyzing the association between IGFI gene polymorphism and performance. In both the Ningdu and Wanzhai Yellow breeds, body weight at 4 months was significantly higher with BB genotype than with AA genotype (p<0.05). Furthermore, body weight at 2 months in the Wanzhai Yellow breeds was also higher with BB genotype than with AA genotype (p<0.05). There were no differences among the genotypes for the other traits studied. Based on these results, it is necessary to do more studies on IGFI before making the IGFI locus into the application of maker-assisted selection programms.